Seed Plants & Gymnosperms

Flashcards about Seed Plants & Gymnosperms: Key Concepts and Definitions

Gymnosperms

Seed plants with ovules and seeds not protected by ovary or fruit tissue.

Heterospory

The formation of two morphologically different spores (megaspores and microspores).

Pollen Grain

The structure that transfers sperm in seed plants, eliminating the need for water in fertilization (though water is still required for the process itself).

Seed

A well-protected resting stage containing tissues from three generations: seed coat, female gametophytic tissue, and the embryo.

Secondary Growth

The process that increases the diameter of stems and roots in many seed plants, leading to thickened woody stems.

Gymnosperm groups

Cycads, Ginkgos, Gnetophytes, and Conifers

Cycads

Palm-like plants found in the tropics and subtropics; possibly the earliest-diverging clade of gymnosperms.

Ginkgos

Gymnosperms with only one living species, Ginkgo biloba, characterized by separation of gender (male and female trees).

Gnetophytes

A group of gymnosperms with about 90 species in three different genera, exhibiting some angiosperm-like characteristics.

Conifers

The most abundant and diverse group of gymnosperms, with reproductive structures in male and female cones.

Megastrobilus

Female (seed-bearing) cone in conifers where seeds are protected by woody scales.

Microstrobilus

Smaller male (pollen-bearing) cone in conifers with scales that are modified leaves beneath which are pollen-bearing microsporangia.

Arils

Fruitlike extensions of the seeds, seen in some conifers (e.g., juniper and yew “berries”), facilitating animal seed dispersal.

Pollination

The process where a pollen grain lands near a female gametophyte.

Ovule

The integument + the megasporangium inside it + the tissue attaching it to the maternal sporophyte.